Intravenous magnesium for cardioversion in fast atrial fibrillation without cardiovascular compromise

Date First Published:
July 27, 2010
Last Updated:
March 30, 2011
Report by:
Dr Aidan Siggers, ST5 Emergency Medicine (Royal Cornwall Hospital NHS Trust)
Search checked by:
Dr Aidan Siggers, Royal Cornwall Hospital NHS Trust
Three-Part Question:
In [atrial fibrillation with rapid ventricular response] is [intravenous magnesium] effective in[cardioversion to sinus rhythm]?
Clinical Scenario:
A sixty-five year old man attends the Emergency Department with a twelve hour history of palpitations. An ECG confirms that he is in atrial fibrillation with a ventricular rate of 130 beats per minute. He has no cardiovascular compromise. You have heard that intravenous magnesium may be an effective and safe way of converting him back to sinus rhythm and wish to review the relevant literature.
Search Strategy:
MEDLINE Pubmed 1950- May 2010
EMBASE 1980- May 2010
Current Controlled Trials (www.controlled-trials.com) May 2010
Cochrane Central Register of Controlled Trials May 2010
National Institute for Health May 2010
Google Scholar May 2010
Search Details:
[{(Magnesium) ti,ab} OR {(mgso4) ti,ab}] AND [{(Atrial Fibrillation) ti,ab} OR ((Atrial) AND (Fibrillation)) ti,ab} OR {(Atrial tachyarrhythmia*) ti,ab}] NOT [{(postoperative) ti} OR {(perioperative) ti} OR {(cardiac surgery) ti} OR {(bypass) ti} OR {(graf*) ti}], LIMIT to Human
Outcome:
145 unique papers of which 8 relevant. One further paper identified on reference search.
Relevant Paper(s):
Study Title Patient Group Study type (level of evidence) Outcomes Key results Study Weaknesses
Magnesium therapy in new-onset atrial fibrillation. Brodsky M, Orlov M, Capparelli E, Allen B, Iseri L, Ginkel M. et al. 1994 USA 18 Outpatients with symptomatic AF duration <7 days and ventricular response 100-200bpm;
Mg 2g over 15 mins then 8g over 6 hours IV plus digoxin by weight (0.375 to 0.625mg) then up to 3 more doses (0.125-0.375mg) versus dextrose placebo with digoxin regime identical
Randomized double-blind study
Mean ventricular rate <90 for over 60 mins; Conversion to SR 100% pts in Mg group reached end point vs. 50% in control group (p<0.05); 60% Mg group converted to SR vs. 38% control group (p>0.05) Poorly defined population and symptom duration, small study, no detail of randomisation or blinding
Intravenous magnesium sulfate versus diltiazem in paroxysmal atrial fibrillation. Chiladakis J, Stathopoulos C, Davlouros P, Manolis A. 2001 Greece 46 new medical admissions with continuous AF <12 hours and ventricular rate >100bpm;
Mg 2.5g bolus IV over 15 mins then 7.5g infusion over 6 hours versus diltiazem: 25mg bolus IV over 15 mins then 12.5mg/hr infusion over 6 hours
Randomized single-blind study
Conversion to sinus rhythm within 6 hours of trial start Conversion to SR in 57% Mg group vs. 22% diltiazem group (p<0.03) Single blinded, no explanation of randomisation,
no placebo group

Magnesium sulfate versus placebo for paroxysmal atrial fibrillation: A randomized clinical trial. Chu K, Evans R, Emerson G, Greenslade J, Brown A. 2009 Australia 24 patients >18yrs attending ED with paroxysmal AF <48 hours with sustained ventricular response >100bpm;
Mg 2.5g in 100ml N saline, infused over 15 mins versus placebo: N Saline 5ml in 100ml N saline over 15 mins
Randomized double-blind study
Heart rate, rhythm, BP at baseline and every 15 mins to 2 hours No difference between groups in HR decrease (p=0.124) or rate of cardioversion (p=0.25) at 2 hours Recruitment bias, HR measurement inappropriate
A randomized controlled trial of magnesium sulfate, in addition to usual care, for rate control in atrial fibrillation. Davey M, Teubner D. 2005 Australia 199 patients >18yrs attending ED with AF and ventricular response >120bpm;
Mg 5g IV with half given over 20 mins then half over next 2 hours versus placebo: Equivalent volume of 5% dextrose IV at same rates of infusion
Randomized double-blind study
HR <100/min; Mean changes in HR at 30/60/90/120/150 mins; Conversion to SR 27% Mg group converted to SR vs.12% control group (p<0.01) Recruitment bias
No AF duration specified
No standardised protocol for "usual care", suboptimal data collection,
short follow up period
The effect of magnesium versus verapamil on supraventricular arrhythmias. Gullestad L, Birkeland K, Molstad P, Hoyer M, Vanberg P, Kjekshus J. 1993 Norway 57 patients with atrial fibrillation, flutter or paroxysmal SVT of duration <7days and ventricular response >100bpm;
Mg 1.2g over 5 mins and further 1.2g after 10 mins if primary outcome not met then infusion 0.04 mmol/min up to 24h versus verapamil: 5mg over 5 mins and 5mg after 10 mins if primary outcome not met then infusion 0.1mg/min to 24h
Randomized single-blind study Conversion to SR/ HR<100/min within 4hr; Conversion to SR within 24h 58% Mg group converted to SR in 4h compared with 19% Verapamil group (p<0.01); 48% Verapamil group had HR <100/min at 4h vs. 28% Mg group (p<0.05) Study population setting not defined, not restricted to AF, no placebo
Effect of magnesium sulfate on ventricular rate control in atrial fibrillation. Hays J, Gilman J, Rubal B. 1994 USA 15 patients presenting to ED with AF and ventricular response >99bpm;
Mg 2g bolus then continuous infusion of 1g/hour for 4 hours plus IV digoxin infusion versus placebo: (composition/regime not specified) plus IV digoxin infusion
Randomized double-blind study
Ventricular rate; Conversion to SR also noted. 3 pts (37.5%) in placebo group converted to SR vs. 1 pt (14.3%) in Mg group Small study, max AF duration not properly defined, placebo and schedule not defined, blinding/randomisation not defined, data from excluded pts not included in analysis
Efficacy of intravenous magnesium sulphate in supraventricular tachyarrhythmias. Joshi P, Deshmukh P, Salkar R. 1995 India 86 patients admitted to general ICU showing AF with ventricular response >160bpm (AF as subgroup of SVTs studied);
Mg 2g IV, same dose at 15 mins if HR >100/min versus verapamil: 5mg IV, Same dose at 15 mins if HR >100/min
Randomized unblinded study
HR; Rhythm; Systolic/diastolic BP effect; Respiratory rate; Symptoms 19.5% Mg group converted to SR vs. 55.5% Verapamil group (p=0.0006) ICU population, inclusion ventricular response very high, AF duration not defined, comorbidities not well defined
Parenteral magnesium sulfate versus amiodarone in the therapy of atrial tachyarrhythmias: a prospective randomized study. Moran J, Gallagher J, Peake S, Cunningham D, Salagaras M, Leppard P. 1995 Australia 42 patients admitted to general ICU with atrial tachyarrhythmia for >1hr, ventricular response >120bpm and Potassium at least 4.0mmol/L;
Mg 37mg/kg over 5 mins then infusion 0.025mg/kg/24hrs versus amiodarone: 5mg/kg loading dose over 15-20 mins then infusion 10mg/kg/24hrs
Randomized unblinded study
Conversion to SR within 24h; Change in HR/SBP Mg group significantly more likely to cardiovert by 24h ICU population, non-consecutive recruitment, unblinded study, no placebo
The acute effects of magnesium in atrial fibrillation and atrial flutter with a rapid ventricular rate. Walker S, Taylor J, Harrod R. 1996 Australia 41 patients attending ED with atrial fibrillation or flutter <48h duration and ventricular response >120bpm;
Mg 5g over 30 mins then digoxin as indicated versus placebo: 20ml N saline over 30 mins then digoxin as indicated
Randomized double-blind study
Conversion to SR; Ventricular rate <100/min; Adverse symptoms No difference between groups in cardioversion at 4 hours Not just atrial fibrillation, small sample size, strict exclusion criteria, inadequate description of randomization/blinding
Author Commentary:
Search strategy was amended as a result of a large body of evidence surrounding AF in cardiac surgery, which was not felt to be directly relevant to the clinical scenario in this case.
Four studies demonstrate, with statistical significance, a more rapid conversion to sinus rhythm in the magnesium group, generally as an adjunct to "usual care", in particular with digoxin. However there is little evidence to support its use as a sole agent as no robust, large study of magnesium alone versus placebo exists.
Bottom Line:
The evidence available to date does not support the use of magnesium as a sole agent for effective rhythm control in fast AF without haemodynamic compromise. It is however demonstrably effective as an adjunct to other agents such as digoxin in both rate and rhythm control, particularly in hypomagnesemic patients.
References:
  1. Brodsky M, Orlov M, Capparelli E, Allen B, Iseri L, Ginkel M. et al. . Magnesium therapy in new-onset atrial fibrillation.
  2. Chiladakis J, Stathopoulos C, Davlouros P, Manolis A. . Intravenous magnesium sulfate versus diltiazem in paroxysmal atrial fibrillation.
  3. Chu K, Evans R, Emerson G, Greenslade J, Brown A. . Magnesium sulfate versus placebo for paroxysmal atrial fibrillation: A randomized clinical trial.
  4. Davey M, Teubner D. . A randomized controlled trial of magnesium sulfate, in addition to usual care, for rate control in atrial fibrillation.
  5. Gullestad L, Birkeland K, Molstad P, Hoyer M, Vanberg P, Kjekshus J. . The effect of magnesium versus verapamil on supraventricular arrhythmias.
  6. Hays J, Gilman J, Rubal B. . Effect of magnesium sulfate on ventricular rate control in atrial fibrillation.
  7. Joshi P, Deshmukh P, Salkar R. . Efficacy of intravenous magnesium sulphate in supraventricular tachyarrhythmias.
  8. Moran J, Gallagher J, Peake S, Cunningham D, Salagaras M, Leppard P. . Parenteral magnesium sulfate versus amiodarone in the therapy of atrial tachyarrhythmias: a prospective randomized study.
  9. Walker S, Taylor J, Harrod R. . The acute effects of magnesium in atrial fibrillation and atrial flutter with a rapid ventricular rate.